1. Field of the Invention
The present invention in general relates to a method of recording and reproducing data. More particularly, the invention concerns a data recording/reproducing method suited for a non-rewritable storage device of the rotation type which is used as an external memory or storage equipment of a computer system and which includes a plurality of tracks.
2. Description of the Prior Art
Heretofore, in the data recording apparatus which constitutes a part of a computer system, there has been no need for recording information indicative of logical erasure or deletion of recorded data on a recording medium at all, because rewritable recording media or easily exchangeable recording media have been employed in all kinds of the conventional recording apparatus.
In reality, when a particular set of recorded data on a rewritable recording medium such as a magnetic disc is to be erased, it is sufficient to delete simply the data set itself or a part of the indexes designating the data set of concern or to write other data at the relevant location. In the case of non-rewritable recording medium of small capacity such as PROM, deletion of data can be readildy accomplished by exchanging the PROM containing the data to be deleted by another PROM loaded with fresh data.
In contrast, in the case of an optical disc utilized as a recording medium of large capacity, it is impossible to accomplish the deletion or rewriting of data once recorded on the recording medium in the manner similar to the data deletion in the magnetic disc and others, because recording of data or information on the optical disc is carried out by forming small holes termed pits in a metallic film deposited over the disc surface through irradiation with a light beam.